Electromagnetic measuring instrument



June 23, 1925. 1,543,529

G. W. SPRENG-ER ELECTROMAGNETIG MEASURING INSTRUMENT Filed April 1l.1924 Inventor-'I George Walter prel'wqer.`

His ATJLor'r-weg.

Patented .lune 23, 1925..

UNITED STATES PATENT OFFICE.

GEORGE WALTER SPRENGER, F LYNN, DIASSACHUSETTS, ASSIGNOR TO GENERALELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

ELEcTnoMA'GNETIc MEAsUR-ING. TNSTEUMEN-r.

Appncauon fued Aprii 11, 1924. seria1 No. 705,957.

VTo all whom t may concern.:

Be it known that I, GEORGE WALTER SPRENGER, a citizen of the UnitedStates, residing at Lynn, in the county of Essex, State ofMassachusetts, have invented certain new and useful Improvements inElectromagnetic Measuring Instruments, of which the following is aspecification.

My invention relates to electric measuring instruments of theelectromagneticV type and in particular to a novel arrangement for in-Acreasing and adjusting the angle of deflection of such instruments.

The electromagnetic instrument is perhaps one of the simpl-est andoldest forms of'indi cating type instruments. Owing to the fact that thedetiection is caused by the action of an electromagnet, generally aplunger magnet, acting against a spring, the defie'ction angle is fairlysmall and not very uniform. In United States Patent No. 394,728, thereis described an instrument of this type where these defects areeliminated tosome extent by providing two plunger magnets with parftially overlapping effects. My invention has for its object a furtherelimination of these defects and in addition an arrangement whereby thedeliection angle may be readily adjusted and the instrument calibrated.

In carrying my invention into effect I use one or more plunger magnetsand I make the winding of the operating solenoid or solenoids in aplurality of sections sep- 3 arated from each other. This arrangementwithout causing saturation of the iron core which forms the movingelement and with? cooling of the coils. By properly adjusting -therelative positions of the severalsections of the solenoid windings, thedeflection characteristics may be made very uniform over a considerablerange of deflection.

Preferably, two solenoids are used and 'p45 arranged on opposite sidesof the axis of rotation of the instrument and in this case correspondingcoil sections of the two solenoids are preferably mounted on theopposite ends of relatively adjustable independent members pivoted onthe axis of rotation so that in adjusting the coil sections of onesolenoid, the coil sections ofthe other solenoid are similarly adjusted.j

The features of my invention which I be- 5 lieve to be novel andpatent-able will be results in an elongation effect of the solenoid fpointed out in the claims appended hereto. For a better understanding ofmy invention, reference is made in the following description to theaccompanying drawing, Fig. 1 of which shows a. top View of the essentialp'art-s of a preferred embodiment of my invention as applied to a curvedrawing instrument, and Fig. 2l showsa side view of the instrument ofFig. 1 omitting the chart supporting members. y

In the drawings, the movable part of the instrument comprises theS-shaped member 10 which is pivoted at its center and having curvedmagnetic core pieces 11 and 12 concentric to the axis of rotation. Themovable member carries in this instance an inkwell 13 which is pivotedon the extremity of one of the radial arms. The inkwell carries acapillary pen arm 14 which dips into the inkwell and is secured in fixedrelation the-reto.' The pen end of the arm 14 cooperrates with asuitable chartwhich is held on the supporting member 15. The penis heldin contact with the chart by a small coiled spring l16 mounted betweenthe pivoted inkwell and its support.V To counterbalance the weight ofthe inlwell an adjustable weight 17 lis provided on the movable member.The member 10 is urged to a Zero indicating position by a coiled spring18 fixed between the member 10 and the stationary lower bearing posts 19rising from the framework 20. Instead of being a curve drawinginstrument, the instrument might be of a. simple indicating type and bythe expression indicating type I intend to include curve drawing as wellas purely indicating instruments and relays which incorporate theessentials of my invention.

rlhe stationary part of the instrument includes members 21, 22 and 23which exten-d in opposite directions from the axis of rotation wherethey are supported by integral collars 24 rotatably mounted on thestationary post 19. Each of these members is separately adjustable aboutthe postl 19 and they may be fixed in any adjusted position by lockscrews 25. On the outer end of the members just described are mountedthe coil sections 26 which, together, form the windings of the twosolenoids with which the core pieces 11 and 12 cooperate. Each suchmember supports Vcorresponding coil sections of the two solenoids and bycorrespending sections I mean for example the first sections in eachgroup. Thus the sections first threaded by the core pieces arecorresponding sections. It so happens in the modication described thatthe correspond-c ing coil sections are diametrically opposite. The coilsections may all be connected in series, in parallel, or in seriesparallel, the only precaution necessary being to see that the coilsections o'l each solenoid produce linx in the same direction. The mostdesir'- able designs will generally result from a series connection ofthe coil sections.

It Will now be evident that the instrument will have acount-ercloclrwise deflection, as viewed vin Fig. l, dependent upon thestrength of the current iiowing in the coils, the magnetic pull of thesolenoids being opposed by the spring 18, and that the range ofdeflectionY fora given variation in the current strength may be madevery small by bringing the coil sections close together or much largerby their separation. Furthermore, itvwill be evident that the deflectioncharacteristics may be changed over a given range of deflection byseparating certain adjacentcoils more or less than other adjacent coils.

' The parts going to make up the instrument may be made in largequant-ities and oi" a standard size Without taking any particularprecautions to see that the individual parts conform to a definitestandard since the deflection characteristics and the calibration of theinstrument may be easily andv A readily altered as soon as the parts areassembled. The solenoid, although made up of standard coil sections oilcylindrical Jform, is sector-shaped con-forming to the circular shape ofthe core and this is advantageous 4because of the diliiculty of Windingsectorshaped coils. By separating the windings into sections in thisWay, a higher current density can be maintained because ot the greaterheat radiating surface which this construction provides.

Although I have shown three groups of coils going to make up a solenoidWinding and have shown two such solenoids, I do not Wish to be limitedin this respect as my invention is not dependent on the number ofsolenoids used nor upon the number of coil sections per solenoid so longas more than one coil section is used for each solenoid and .respect toeach other.

In accordance With the provisions of the patentf statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof;but I desire to have it understood that the apparatus shown anddescribed is only illustrative and that the invention can be carried outby other arrangements.

What I claim as new and desire to secure by Letters Patent of the UnitedStates,

1. An indicating instrument of the electromagnetic type having anoperating plunger magnet the Winding of which is made up ot a pluralityof separate coil sections Which are relatively1 adjustable with respectto each other along the axis of Vthe solenoid.

2. An indicating instrumentof' the electromagnetic type having a sectorshaped operating solenoid forming the stationary part ot the instrumentand made up lof a plurality of separate cylindrical coil sectionsarranged to be Vindependently adjustable along the axis of the solenoid.

3. In an indicating instrument of the electromagnetic type, a movingelementmade up of an S-shaped member pivoted at its center, the endportions of the member comprising sector shaped core pieces, -sectorshaped solenoids forming the stationary part of the instrumentpositioned to be threaded by said core pieces, said solenoids being madeup of a plurality of coil sections, the number of coil sections in eachsolenoidfbeingthe same, and independently adjustable supporting memberspivoted on the axis of rotation of theS-shaped member -for supportingcorresponding coil sections of each solenoid. y Y

4. An indicating instrument of the plunger magnet type having a sectorshaped core member, supporting means therefor pivotedV for rotationaboutthe central axis of the sector, a relatively stationary solenoid mem'-bcr arranged to be threaded by said core, said solenoid member beingmade up of va plurality of coil sections,supporting members for eachcoil section, said supporting members being pivoted on the axis ofrotation of the core member and independently adjustable about saidaxis.

In Witness whereof, I have hereuntoA set my hand this eighth day o'tlApril, 1924.

GEORGE VALTER SPRENGER.

